Safety mechanism for a plastics injection-molding machine

Claim 2

In a plastics injection-molding machine in which one of a pair of platens for mounting mating mold halves respectively thereon is movable toward and away from the other for mating and separating said mold halves, safety drop-bar mechanism selectively operable for preventing a mating approach of the platens from their separated positions, such mechanism comprising a bar mounted on the machine in approximate axial alignment with the direction of movement of said one platen, said bar being pivotally mounted at one end on the machine for swinging movement of the bar to move its other end selectively into and out of the path of movement of said one platen when said platen is separated from the other platen for engaging the one platen and preventing it from moving toward the other, and means for selectively moving the bar into and out of said path of the one platen, said means for selectively moving the bar into and Out of said path comprises a shaft rotatably supported on the machine, a crank fixed on the shaft, a link pivotally connected at one end to the crank and at the other end to the bar at a location offset from the pivotal mounting thereof, said crank and link and shaft being arranged for actuating the bar into said path by rotation of the shaft in one direction and out of said path by rotation in the opposite direction, and means for rotating the shaft selectively in opposite directions.

Claim 3

In a plastics injection-molding machine in which one pair of platens for mounting mating mold halves respectively thereon is movable toward and away from the other for mating and separating said mold halves, safety drop-bar mechanism selectively operable for preventing a mating approach of the platens from their separated positions, such mechanism comprising a bar mounted on the machine in approximate axial alignment with the direction of movement of said one platen, said bar being pivotally mounted at one end on the machine for swinging movement of the bar to move its other end selectively into and out of the path of movement of said one platen when said platen is separated from the other platen for engaging the one platen and preventing it from moving toward the other, and means for selectively moving the bar into and out of said path of the one platen, said means for selectively moving the bar into and out of said path comprises a shaft supported on the machine for rotation in a plane at right angles to and spaced from the plane of movement of the bar, a crank fixed on the shaft, a link pivotally connected to the crank at one end with its other end pivotally connected to the bar at a location offset from the pivotal mounting thereof, said crank and link and shaft being arranged for actuating the bar into said path by rotation of the shaft in one direction and out of said path by rotation in the opposite direction, stop means limiting the pivotal movement of the bar into said path at a predetermined point therein, and a handle for rotating said shaft, said handle being of such mass, eccentric to the shaft and being so angularly attached to said shaft as to overbalance the shaft in said one direction when the bar has been positioned into said path, thereby holding the bar in the path-blocking position determined by said stop means.

Claim 4

In a plastics injection-molding machine in which one pair of platens for mounting mating mold halves respectively thereon is movable toward and away from the other for mating and separating said mold halves, safety drop-bar mechanism selectively operable for preventing a mating approach of the platens from their separated positions, such mechanism comprising a bar mounted on the machine in approximate axial alignment with the direction of movement of said one platen, said bar being pivotally mounted at one end on the machine for swinging movement of the bar to move its other end selectively into and out of the path of movement of said one platen when said platen is separated from the other platen for engaging the one platen and preventing it from moving toward the other, and means for selectively moving the bar into and out of said path of the one platen, said means for selectively moving the bar into and out of said path comprises a shaft supported on the machine for rotation in a plane at right angles to and spaced from the plane of movement of the bar, a crank fixed on the shaft, a link pivotally connected to the crank at one end with its other end pivotally connected to the bar at a location offset from the pivotal mounting thereof, said crank and link and shaft being arranged for actuating the bar into said path by rotation of the shaft in one direction and out of said path by rotation in the opposite direction, stop means limiting the pivotal movement of the bar into said path at a predetermined point therein, and a handle for rotating said shaft, said handle being of such mass, eccentric to the shaft and being so angularly attached to said shaft as to overbalance the shaft in said one direction when the bar has been positioned into said path, thereby holding the bar in the path-blocking position determined by said stop means.

Claim 5

The mechanism in accordance with claim 2, in which said stop means comprises a projection on the crank-connected end of said link, said projection extending outward from said end in position to be brought into engagement with a portion of said shaft when the shaft is rotated in the direction to position the bar in the path-blocking position, which engagement prevents further rotation of the shaft in the latter direction.

Claim 6

The mechanism in accordance with claim 2, which includes stop means for limiting the pivotal movement of the bar when it reaches a predetermined point clear of said path.

Claim 7

The mechanism of claim 4, in which said second stop means is provided by so connecting the link to the crank that the crank radially overlaps a part of the shaft, and such that the bar is in platen-clearing position when the shaft is rotated to the point of link-interference with the shaft.

Claim 8

The mechanism of claim 2, in which the connections of said link are in substantial alignment with said shaft when arrested by said stop means; whereby the dead center relation of linked parts, in the platen-blocking position of said bar, assures removal of said bar only by deliberate actuation of said handle.